Modeling ferroelectric properties in systems of induced and permanent dipoles

In earlier studies we reported on Monte Carlo simulations of dielectric properties in systems of permanent or induced dipoles considering electrostatic interactions. The calculations are expanded now to systems composed of induced and permanent dipoles with the final purpose to model ferroelectric properties in structures like BaTiO₃ . In a first step a dipole chain with permanent dipoles (Ti-ions moving in double well potentials) and induced dipoles (O-ions) in alternating order is considered referring to the [001] crystal direction in BaTiO₃. The calculation yields a hysteresis loop of the polarization, a Curie-Weiss law, a temperature dependent remanent polarization, and a spontaneous polarization. A second system refers to the (200) plane of BaTiO₃. Besides a hysteresis of the polarization with a temperature dependent remanent polarization, we find spontaneous ferroelectric domains with an uniform polarization. Typical ferroelectric properties arise if permanent and induced dipoles are involved in the interaction process